Since the main plain and basin areas in the Yellow River basin are regions of great importance to the social and economic development of China, it is important work to understand the groundwater balance and circulation in these regions. We have selected the Yellow River source region and the Yinchuan, Hubao, Taiyuan and Guanzhong basins, as well as the Lower Yellow River zone for study on groundwater balance and circulation. This paper shows characteristics of stable isotope ratios of hydrogen and oxygen, and water quality in the main plain and basin areas in the Yellow River basin. Moreover, the groundwater fl ow system and water balance in these regions are estimated by the results